Monday, April 27, 2009

The Flu Exponential

Let's make some back-of-the-envelope calculations (just for fun).

Swine flu is starting its exponential increase in most advanced countries in parallel, from a small base. So it suffices to consider England. Assume that we start with 16 infectious cases today and that the number of infected individuals doubles every day.

Then in 10 days we have 16,000 cases; in 20 days we have 16 million cases and the "whole population" is infected at day 22. That's comfortably by May 19th.

Since the global population today is closely connected both by air transport and in dense conurbations (starting with Mexico) there is no evolutionary advantage to the virus to hang around in the host. The ones which trash the human victim to reproduce as rapidly as possible will have most offspring. So expect the virus to get more virulent.

We were in the supermarket this morning and noticed neither extra shoppers nor a run on canned food. It will be interesting to see the situation in 10 days time.

Note that if it gets really serious, then essential services such as water and power may also be interrupted so the idea that one can just stock up, ease back from socialising and catch up with a backlog of reading or TV-watching seems unduly optimistic (not to mention callous).

So far it's a dress-rehearsal for the putative future bird-flu pandemic, but we shall see.

Jokes about Swine Flu.